Siblings, or Something
by Judylwb Idoov
Summary: Working title. Mabel and Dipper are back at the Mystery Shack for a second summer of fun, but their growing feelings for each other and the mysteries of Gravity Falls promise to cause complications. Pinecest, because their character chemistry is too strong. The story is T for now, but might become M later, I don't know. Any reviews or criticism is gladly welcome :)
1. Welcome Home

"Sweep, sweep, sweep" hummed Soos, the resident repairman and janitor of Gravity Falls' number one curios and con center, the Mystery Shack. It was days like these where Soos could finally allow himself some breathing room to relax.

He sighed and glanced at the clock. With the wave of supernatural and highly dangerous beings and monsters that hit Gravity Falls during the summer, his schedule had been fully booked with things like running from Gnome giants and hunting down man-eating spider ladies. Although these adventures were always dangerous, that was for sure, he always had fun on them, because he braved these quests with his two favorite people, the Mystery Twins: Mabel and Dipper Pines.

" _Ah, the Pines twins. They'll be a sight for sore eyes"_ thought Soos. They were arriving in a couple days for Summer Vacation for the second consecutive year.

Soos' reminiscing came to an abrupt stop when he heard a particularly loud creak. Looking down at his feet, he noticed an indentation in the carpet. Lifting the carpet, he found a handle. "Must be a trapdoor…"

It was a sleepy afternoon in Gravity Falls – unless, of course, you were an employee of the Mystery Shack. Stan Pines scurried about, brandishing a broken broom in one hand, and a bent frying pan in the other. "Soos, hurry and grab the net!" he shouted. The handyman made a dash from behind the tipped couch for the coffee table, and raised the net in the air. Wendy was helping to distract the bat with the hatchet she kept on-hand at all times.

For the past two days, these three had been holed up in their place of business, all because of the giant poisonous bat that was currently demolishing the living room. It had escaped from Ford Pines' secret basement for document and specimen storage, which Soos had discovered. He had a knack for that kind of thing. How the bat had survived that long, no one knew.

 _Stan was researching the thing destroying his house in one of the copies he had made of his brother's Journals, and found out that if it were able to interbreed with normal bats, the resulting mutation would be even more dangerous, and therefore it had to be contained. That's why, when he heard a knock at the door, he shouted for Soos not to answer it. Without an answer at the door, Wendy turned around. "Sweet, not workin' today, I guess!" she said, when she heard the door creak open, and Soos whisper "Wendy? Hurry, get in here!" Intrigued by Soos' mysteriously hushed tone, she quickly went for the door. As soon as the redhead was through the door, Soos blocked off the entrance with a dresser. "Aren't you gonna help me?" he asked._

A knock at the door caused all four of them to turn their heads. "Grunkle Stan? Soos?" yelled a familiarly high-pitched and cutesy voice. "Wendy?" yelled an equally high-pitched, if not slightly less cute and more cracky voice. _"Ah, crap, it's the kids."_ Thought Stan. _"Were they really supposed to arrive today?"_

"Uh, kids? Hey, this isn't really a good time for you guys to be here." Said Stan.

"Uh-huh, and why's that, you cranky old man?" responded Dipper Pines.

Mabel gasped and then added with a grin, "Do you have a girl in there? I knew it! C'mon, spill the beans Stan!"

"Well, _I'm_ in here with him, but–" said Wendy, but she was instantly interrupted by Dipper.

"What!?" shouted Dipper, a knee-jerk response. His mind fired on all cylinders, thinking a million different things at once.

" _Why is she here? Does she have a boyfriend? Is she dating Stan? Are they intimate? Why wouldn't she tell me about it? Why would she date Stan?"_

He liked to consider himself above child-like crushes, being a whole _year_ older than last year. Even still, he couldn't deny his feelings for the redhead bombshell.

"– But it's not like _that_ , Dipper." Finished Wendy, glancing over at Stan in his tank-top and underwear. "Ew. The only thing I'm interested in right now is the weird three-eyed bat thing that's trying to eat us!"

The twins looked at each other, released a simultaneous sigh of relief and nodded. They charged the door, breaking down its rusty and molded hinges. They saw the bat monster and tackled it to the floor.

When it hit the ground, it hissed, sputtered and evaporated in a puff of smoke, with a loud bang. The sudden empty space between the two twins caused them to collapse, Dipper landing awkwardly on top of Mabel. He felt the rise and fall of her chest. Dipper hadn't really paid it much mind until now, but she definitely _had_ a chest tofeel. _"Gross."_ Thought Dipper, shaking his head. This was his _sister_ , it was probably just the adrenaline. The two blushed and laughed awkwardly before standing up. Brushing themselves off, Dipper looked up to see Soos, Wendy and Stan staring with jaws gaping at the Mystery Twins.

"What? You know that bats are–" "–More afraid of you than you are of them!" Dipper began, only to be interrupted by Mabel. "I taught you that!" said Mabel. The two shared a chuckle and glanced around at the mess that the two-day ordeal had caused. "Hi, Grunkle Stan. I see this place is in the same state as when we left" mocked Dipper. "Yeah, and you two brats aren't any different either!" responded Stan, dropping his makeshift weapons, running for the twins and trapping them in a stranglehold of a bear hug. Soon, the two Shack employees joined in.

"Great to have you back dudes" said Soos. "Yeah, the school year totally blew without you guys here" added Wendy.

"Great to be back" responded Dipper and Mabel in unison.

They closed their eyes, and released a contented sigh.

They were home.


	2. Vacation

After having cleaned up the mess for Grunkle Stan ("You guys killed the monster, so it's your mess to clean up!"), the twins climbed the familiar flight of stairs for the first time in a long, long time. The door creaked open slowly, and the smell of dust, must, and pre-teen spirit flooded out. Taking a deep breath, Dipper spoke first. "I guess we should pick our beds, then."

"Way ahead of you, slowpoke!" responded Mabel, having already unzipped her suitcase, as she began to hang her various posters. These posters ranged from pictures of kittens paired with motivational mantras to promotional material for the most recent Sev'ral Timez album, "Sum'rtime Jamz". Dipper sat down on his bed after unpacking his over-stuffed backpack and suitcase. He took a deep breath as he laid back and stared at the roof of the attic, and smiled contentedly.

"Whatcha doin', Dipper?" questioned Mabel. "Tryin' to spot all the old mold patches?"

"Nah, Mabes, just takin' it all in" he responded. "It feels so good to be back."

Mabel gave him a questioning look. "Gettin' sentimental on me?" she asked.

He turned to her and responded "Aren't you?"

Mabel paused and thought about it. They chose to come up here for Summer Vacation, but she thought that was just because it was the cheapest option, considering they wouldn't need to pay for housing. Sure, she was happy to see Stan, Soos, and all the others, but really it wouldn't have been her first choice. _"Why wouldn't it have been?"_

Dipper started, "I really love this place. Think about all the good times we've had here. All the supernatural adventures we've had might've been dangerous, but they were the most fun I've ever had on a vacation."

Mabel couldn't argue with that. Once you had been kidnapped by gnomes in an attempt to make you their queen, nothing else could really compare.

He continued, "When we finally had to leave this place, I can't help but feel I left a piece of myself here. Now we're teenagers, sophomores in high school, and I miss those days more than ever. They remind me of a happier time we had together."

In high school, Mabel and Dipper had found different groups that catered to their interests. Mabel joined the Drawing Club, Cooking Club, and Cheerleading. Dipper went on to join the Chess Club and Debate Team. The only opportunity that they had to see each other during school, aside from sightings in between classes, was in Glee Club. Mabel had conned Dipper into joining the Glee Club during Freshman year, convincing him that it would increase his charm tenfold to the ladies. He only stuck around for the second year because they would occasionally sing Top 40 Hits songs for their performances.

"Ever since we split, we've been drifting away from each other. We haven't talked as much, we barely see each other in person."

Their parents had divorced shortly after the twins returned from their first trip to Gravity Falls. It turned out the trip had all been to shelter the kids from the fallout of their parents' failing marriage. They rarely saw each other outside of school and holidays now, Dipper living with their Dad, and Mabel with their Mom. This return to the Falls had been an orchestration of Dipper's and Mabel's. They stayed in touch online, and decided that if they pooled their funds, a vacation would be significantly easier on their wallets. That was it, a financial convenience.

"That's the _real_ reason I wanted to come here with _you_. I figured this was a chance to rekindle our relationship before we lost each other for real, like Stan and Ford did."

Mabel frowned. She looked at Dipper. He had grown since their last time here, of course. His hair was shorter and less unruly. Ever since he had begun to live with his Dad, he had started to wear more than one outfit all the time. He was no diva, but he certainly didn't look like a bum off the street. He would normally forgo the Pine Tree-emblazoned cap in public, but he had kept it close all these years. He had taken it with him on this trip, and had been wearing it since they got in the car with their GPS set to Gravity Falls, Oregon. He was _handsome_ now. But there was pain in his eyes, most certainly from the flood of memories that being here, right now, in the Shack, with his sister had brought back.

She walked over to Dipper's side of the room, and sat down next to him. She let out an exasperated sigh.

Mabel wasn't quite the same little girl from their last visit either. She had kept her hair long, with the curls at the ends of the strands. She had never abandoned her potpourri of sweaters, though at school she had begun to favor the less ridiculous ones. Today she wore her favorite one, the pink sweater with the Shooting Star. It was so _her_. She wore a purple skirt to match, and a pink headband. She too had grown physically, maintaining her millimeter lead in height on Dipper. Her other features had filled out too, with healthy C-cup breasts, and a nicely-sized butt, enough to be proud of. There was a tear forming in her eyes, though. Dipper's words had moved her.

Dipper readied himself. "I came here with you because, well, you-you mean a lot to me, and I don't want to lose you." He closed his eyes and cringed, awaiting the mocking remark from his sister.

It never came. Instead, he felt a pair of arms wrap around him. Tears flowed from Mabel's eyes, and she held her brother tightly.

"I love you too, Dip-stick" she said. Dipper was surprised at first, but he soon accepted it and began to return the hug.

Mabel went on, "Let's *sniff*… Let's make this the best Summer Vacation ever, bro-bro!"

Dipper smiled. Before they had a chance to revel in their renewed relationship, a shout from downstairs interrupted them. "MABEL! DIPPER! Get down here! We've got some catching catching up to do!" came Wendy's voice.

"Yeah, kids! I'll even have Soos make us some dinner!" added Stan.

Mabel didn't want this hug to end, it felt so _right_ , laying in each other's arms. Dipper gave her one final squeeze, then stood up. "We'd better get down there, heh" said Dipper, smiling and extending a hand to Mabel.

Mabel took his hand, using it to pull herself up. She wiped the tears from her face, and returned the smile. "Yeah, let's get down there before Soos burns down the kitchen!" she responded.

"Race ya down the stairs!" she continued, and pushed him aside. Dipper laughed and called back to her "No fair! Headstart!"

* * *

 **Quick Note:** Thank you guys so much for the reads so far, it's great to see my first story _actually_ getting some people who like it. :) Also, for those who didn't know, I changed some things about the first Chapter, and in my opinion, it's a significantly better version of the same thing. Sorry, it took so long for this chapter to get up, I hit some issues in my personal life, and for some reason I couldn't bring myself to write for a couple days straight. Either way, hope you enjoyed, and thanks for reading!


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